Is it permissible to purchase an entry visa to France for 15 million [currency units] if the state will not grant it, and is this act considered a bribe from a Sharia perspective?

The ruling on purchasing a visa is tied to the ruling on traveling to that country. If it is permissible to travel, then purchasing the visa is permissible, and vice versa. If the purchase is a bribe to obtain the visa, then paying it is permissible if it is the only means to undertake a permissible journey. In such a case, the warning against bribery applies to the recipient, not the payer.